Radial arm saws generally have a horizontal support for the workpiece. The saw blade is mounted on a motor over the work support by a mechanism enabling horizontal translatory motion in an adjustably preset path. When the path is not at right angles to the long axis of the workpiece, it is called a miter cut. When the saw axis of rotation is tilted from the horizontal, the blade makes a bevel cut. A cut that is both bevel and miter is called a compound bevel out. For accurate operation, the user must be able to predict the precise path the saw blade will take through the workpiece.
In conventional radial arm saws, the rotatable saw blade, or other cutting tool mounted in place of the saw blade, is mounted in a yoke, carriage, track arm and column which cooperatively support the blade in different positions for cutting. The saw blade rotation axis and plane are offset from the central axis of the yoke. As a result, a number of difficulties and disadvantages are encountered in controlling the operating angles of the cut. There have been a number of patents issued for saw assemblies which cause the bevel angle or rotation of the saw axis about a horizontal axis to be better controlled. U.S. Pat. No. 3,302,669 issued Feb. 7, 1967 to Edler teaches a large arcuate support for the motor assembly. The center of the arc coincides with the bottom tangent of the blade edge so that movement of the motor assembly around the arc for bevel cuts always places the bottom of the saw kerf at the same position on the work surface. The disadvantages of this structure relate to the difficulties of accurately and securely supporting the weighty, vibrating motor assembly at selected points along the sliding arcuate support when great torque forces are applied during the cutting operation. U.S. Pat. No. 4,152,961 issued May 8, 1979 to Batson teaches pivoting of the entire radial arm assembly about a central pivot with a locking pin riding in an arcuate guide slot. Supporting the entire weight of the arm and motor assembly about a single pivot far away from the center of mass and torque inherently taxes the accuracy and rigidity of the entire system.
A system for predictably positioning the kerf location as the blade is tilted for bevel cutting. that will ensure secure and accurate support for the blade during bevel cutting would enhance the utility of radial arm saws and related apparatus.